Ali Rowghani Departs After CEO Costolo Sought to Run Product Team; Head of North American Media Also Leaving

Twitter Inc.'s leadership was thrown into disarray Thursday after one of its top executives, Ali Rowghani, resigned as chief operating officer amid a dispute with Chief Executive Dick Costolo.

The sudden resignation of Mr. Rowghani, a well-respected manager who in his four years at Twitter rose to become Mr. Costolo's most-trusted lieutenant, comes at a particularly thorny time in the company's young history as a public company....